SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66e73ac5df142fd6e6bf36b1192554a364f547b8bc3fbff2eb7c4869f93f7e09' 
  AND token = 'MBvGE29Ik24pWndzaY5D8c+SP/ZPxFkMjK8bhKUgipw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}